How-To: Install Rostra Universal Lumbar Kit
This tutorial will describe how to install the Rostra Precision Controls Universal Lumbar Kit in the Cruze.
Part Number & Cost
Rostra 250-1752; $99 Retail
A group buy is currently available as of 01/20/15 to get the kit for $69 plus shipping:
Required Tools and Materials
- T500 Torx bit. A high quality T50 worked for me but a T500 is a better fit and is made for a higher torque spec.
- 10mm socket
- Wire stripper
- Terminal crimper
- Utility knife with new blade
- Roll of 16 gauge red wire
- Roll of 16 gauge black wire
- Two insulated 1/4" female slide-on connectors/terminals
- One 1/4" stud ring terminal
- One wire splice
- Roll of fleece tape
- Extra zipties
Before I begin, I want to mention a few things. This will not be the only way to install this kit, but it is effective and modular. While installing this kit, you will see pictures that will look a tad different from what you will see with regard to the seat cover. When I bought my Cruze Eco, I had the seats upholstered with leather by a local shop that the dealer used, so taking apart the seat may be a different process for you. I will outline the process I took, and you will have to evaluate how your own seat cover is removed to determine how to get to the back of the seat.
To begin, you will need to access the rear of the seat. Slide the seat all the way forward. Using a T50 torx bit, you will need to remove the two bolts that hold down the seat rails. On my car, I had to get an impact wrench to get these off because they were on tight, so make sure you can loosen those bolts first before you do anything.
Once you get the bolts loosened, lift the rear of the seat, and the front should slide out. The front only hooks into the sheet metal; it isn't bolted down.
Disconnect the battery ground in the enigne bay.
In my particular car, I had to lift a flap that covered the lower part of the seat. After doing so, I noticed that the seat cover was held together using these wire fasteners.
I removed fasteners to allow me to slide the bottom part of the seat cover out of the way.
Once you've separated the seat covers, you will be able to see the wire mesh that holds the seat foam. You will need to slide the bladder between the spring mesh and the seat cushion. You can review Boraz's writeup to see how this was done on the OEM leather seats:
Note: Boraz' writeup will look a bit different as he used the large bladder in his kit. The kit I recommend is the medium sized bladder according to the part number listed at the top of this tutorial.
Once you have the bladder installed, secure it with zipties. Be sure to position it where you want lower back support to be. If needed, sit in the passenger seat. I would recommend the position I chose below.
Following the second picture above, I cut the zipties and re-attached the bladder. The reason is the ziptie orientation. When you cut off the excess strip from the ziptie, a somewhat sharp end will protrude. The way I initially had it, the sharp end would protrude out toward the back of the seat. I was worried that if someone sat in the back and pressed their knees against the back of the seat, it could eventually cause a tear. Be mindful of this when you tie down the bladder.
I ran the hose for the bladder through the opening where the wiring harness goes through. While I did not show it in this picture, I wrapped the hose with fleece tape and also taped it together with the wiring harness.
Underneath the seat, I mounted the pump in the following location. Note: if you have a power seat, you will need to find a different place to mount the pump.
Remove the trim on the floor to the left of the seat. You will need to work your way forward from the back, lifting up on the back and then pulling rearward to get the part under the console out.
Next, we will make the wiring harness. Start with a strip of red and blue wire. Strip each end and crimp the slide-on connectors like so. To the left are the new wires, and to the right is the wiring harness that the kit comes with. Wrap the wire with fleece tape, and slide it through underneath the floor of the seat so it comes out as shown below.
With the floor trim removed, you will find a ground point. Cut the black wire according to the correct length to reach that ground point, strip the wire, crimp on the 1/4" ring terminal, remove the 10mm nut, place the wire over the stud, and re-tighten the nut.
Next, remove the fuse box cover right above where you were just working. You will need to detach the fuse box and pull it through the opening. To do this, there are two tabs at the top of the fuse box. Pull them toward each other with one hand, while using the other hand to push the fuse box from the back. You will have to reach behind the dash to do this.
Once you have the fuse box pulled back, it will be resting on two channels as shown below. Simply side it up.
To clear the opening, you will need to twist it to the left.
Flip the fuse box over. On the back, there is a black cover. Remove that cover.
Run your red wire to the back of the fuse box and cut the wire. Refer to the image below to see how long it needs to be. Splice into one of the 20A auxiliary circuits. The one I chose had a purple wire as shown below.
Reattach the black cover and reinstall the fuse box.
Reinstall the floor trim.
The next part will involve cutting a hole in the seat to mount the switch. Don't do what I did. I figured it would look good in the middle, which it does, but the reality is that right behind this point, there is some molded plastic (which doesn't appear to serve any purpose in my car), but made my job all that much more difficult. In short, verify what is behind where you will be cutting to ensure that you have the necessary clearance. Refer to the following images not as a recommended switch mounting point, but simply to show you how the switch is mounted. I repeat, do not use the location I used for mounting the switch.
I used the little plastic tab to outline where I was going to make the cut. Slowly and carefully using the utility knife, cut an outline of where the switch will be mounted. Alternately, you can use a pencil.
Slowly carve a deeper groove into the plastic. Be VERY careful not to push too hard, or the blade may slip and you'll end up leaving an unsightly grove in the plastic. Work slowly and patiently. Eventually, you will be able to push the blade clear through the plastic.
Finish cutting the piece out, then test fit the switch. Enlarge the mounting hole by shaving off more plastic as needed.
Connect the two female slide connectors to the male slide connectors in the kit's wiring harness and tuck them into the floor opening.
Connect the wiring harness to the pump and to the switch.
Connect the battery ground you should have disconnected earlier.
Test to make sure the kit works.
Ziptie the wiring to the underside of the seat to keep it tidy, but make sure to leave enough room for the seat to move forward and backward without pulling on the wire.
Slide the seat back into its latched position and reinstall the seat rail mounting bolts.
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